<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
    <script>
        $(function() {
            var d01 = document.getElementById("d01");
            var $aaa = $(d01);
            $aaa.css("font-size", "48px");

            var li = document.getElementsByTagName("li");
            // var $li = $(li[0]);
            // alert($li.html());
            // $li.each(function() {
            //         alert($(this).html());
            //     })
            ///alert($li.html());

            var $li = $(li); //DOM转jquery
            var li01 = $li.get(0); //jquery对象转DOM
            alert(li01.innerHTML);
        });
    </script>
</head>

<body>
    <DIV id="d01">SDFSDFSDF</DIV>

    <ul>
        <li>sdfs1</li>
        <li>sdfs2</li>
        <li>sdfs3</li>
        <li>sdfs4</li>
        <li>sdfs5</li>
    </ul>

</body>

</html>